Systems and methods for computing accurate load impedance in the presence of measurement accuracy-reducing events

The present disclosure relates in general to electronic devices, and more particularly, to a flexible approach to computing accurate load impedance in the presence of measurement accuracy-reducing events.

Many traditional mobile devices (e.g., mobile phones) include one or more cameras for capturing images. To provide for image stabilization and focus, a position of a camera within a plane substantially parallel to a subject of an image as well as a position of a lens of the camera in a direction perpendicular to such plane, may be controlled by a plurality of motors under the control of a camera controller. A control system may be implemented using an applications processor of the mobile device coupled via a communication interface (e.g., an Inter-Integrated Circuit or I2C interface) to a camera controller local to the camera and its various motors. For example, the applications processor may communicate to the camera controller a vector of data regarding a target position for the camera, whereas the camera controller may communicate to the applications processor a vector regarding an actual position of the camera, as sensed by a plurality of magnetic sensors (e.g., Hall sensors) and/or other appropriate sensors.

A camera controller may receive a number of disparate-rate data streams and sub-streams, which it must manage and deliver to other processing components for processing of data in order to control components (e.g., motors) of the camera. Other control systems, including those used in devices other than for cameras, may also receive a number of disparate-rate data streams and sub-streams, which must also be managed and delivered to other processing components for processing of data in order to provide control of one or more components. Among such disparate-rate data streams and sub-streams may be measurements of current and voltage of a load (e.g., a voice coil motor) associated with the camera control. Such asynchronous measurements of current and voltage may present challenges in accurately computing impedance of the load, which may be required for control of such load.

In accordance with the teachings of the present disclosure, the disadvantages and problems associated with measurement of impedance of a load in certain systems that experience measurement accuracy-reducing events may be reduced or eliminated.

In accordance with embodiments of the present disclosure, a system may include a first controller and a second controller communicatively coupled to the first controller via a bidirectional communication channel and configured to drive a load in accordance with a target current signal, sample a load voltage of the load at a sample rate substantially slower than a time duration of electrical transients of the load, calculate a resistance of the load based on a current signal and the load voltage and communicate information indicative of the resistance to the first controller at a time interval substantially slower than the time duration of electrical transients of the load, detect when one or more accuracy-reducing events associated with the system occur, wherein an accuracy-reducing event is one which negatively affects accuracy of calculation of the resistance, and modify the information provided to the first controller when one or more accuracy-reducing events occur.

In accordance with these and other embodiments of the present disclosure, a method is provided for a system comprising a first controller and a second controller communicatively coupled to the first controller via a bidirectional communication channel. The method may include, by the second controller, driving a load in accordance with a target current signal, sampling a load voltage of the load at a sample rate substantially slower than a time duration of electrical transients of the load, calculating a resistance of the load based on a current signal and the load voltage and communicate information indicative of the resistance to the first controller at a time interval substantially slower than the time duration of electrical transients of the load, detecting when one or more accuracy-reducing events associated with the system occur, wherein an accuracy-reducing event is one which negatively affects accuracy of calculation of the resistance, and modifying the information provided to the first controller when one or more accuracy-reducing events occur.

Technical advantages of the present disclosure may be readily apparent to one having ordinary skill in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure.

illustrates a block diagram of selected components of an example mobile device, in accordance with embodiments of the present disclosure. As shown in, mobile devicemay comprise an enclosure, an applications processor, a microphone, a radio transmitter/receiver, a speaker, and a camera modulecomprising a cameraand a camera controller.

Enclosuremay comprise any suitable housing, casing, or other enclosure for housing the various components of mobile device. Enclosuremay be constructed from plastic, metal, and/or any other suitable materials. In addition, enclosuremay be adapted (e.g., sized and shaped) such that mobile deviceis readily transported on a person of a user of mobile device. Accordingly, mobile devicemay include but is not limited to a smart phone, a tablet computing device, a handheld computing device, a personal digital assistant, a notebook computer, a video game controller, or any other device that may be readily transported on a person of a user of mobile device.

Applications processormay be housed within enclosureand may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, applications processormay interpret and/or execute program instructions and/or process data stored in a memory (not explicitly shown) and/or other computer-readable media accessible to applications processor.

Microphonemay be housed at least partially within enclosure, may be communicatively coupled to applications processor, and may comprise any system, device, or apparatus configured to convert sound incident at microphoneto an electrical signal that may be processed by applications processor, wherein such sound is converted to an electrical signal using a diaphragm or membrane having an electrical capacitance that varies based on sonic vibrations received at the diaphragm or membrane. Microphonemay include an electrostatic microphone, a condenser microphone, an electret microphone, a microelectromechanical systems (MEMs) microphone, or any other suitable capacitive microphone.

Radio transmitter/receivermay be housed within enclosure, may be communicatively coupled to applications processor, and may include any system, device, or apparatus configured to, with the aid of an antenna, generate and transmit radio-frequency signals as well as receive radio-frequency signals and convert the information carried by such received signals into a form usable by applications processor. Radio transmitter/receivermay be configured to transmit and/or receive various types of radio-frequency signals, including without limitation, cellular communications (e.g., 2G, 3G, 4G, LTE, etc.), short-range wireless communications (e.g., BLUETOOTH), commercial radio signals, television signals, satellite radio signals (e.g., GPS), Wireless Fidelity, etc.

Speakermay be housed at least partially within enclosureor may be external to enclosure, may be communicatively coupled to applications processor, and may comprise any system, device, or apparatus configured to produce sound in response to electrical audio signal input. In some embodiments, speakermay comprise a dynamic loudspeaker, which employs a lightweight diaphragm mechanically coupled to a rigid frame via a flexible suspension that constrains a voice coil to move axially through a magnetic gap. When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the voice coil, making it a variable electromagnet. The voice coil and the driver's magnetic system interact, generating a mechanical force that causes the voice coil (and thus, the attached cone) to move back and forth, thereby reproducing sound under the control of the applied electrical signal coming from the amplifier.

Cameramay be housed at least partially within enclosure(and partially outside of enclosure, to enable light to enter a lens of camera), and may include any suitable system, device, or apparatus for recording images (moving or still) into one or more electrical signals that may be processed by applications processor. As shown in, cameramay include a plurality of mechanical actuators, sensors, and image capturing components.

Image capturing componentsmay include a collection of components configured to capture an image, including without limitation one or more lenses and image sensors for sensing intensities and wavelengths of received light. Such image capturing componentsmay be coupled to applications processorsuch that cameramay communicate captured images to applications processor.

Mechanical actuatorsmay be mechanically coupled to one or more of image capturing components, and each mechanical actuatormay include any suitable system, device, or apparatus configured to, based on current signals received from camera controllerindicative of a desired camera position, cause mechanical motion of such one or more image capturing componentsto a desired camera position. An example of a mechanical actuatoris a motor.

Sensorsmay be mechanically coupled to one or more of image capturing componentsand/or mechanical actuatorsand may be configured to sense a position associated with camera. For example, a first sensormay sense a first position (e.g., x-position) of camerawith respect to a first linear direction, a second sensormay sense a second position (e.g., y-position) of camerawith respect to a second linear direction normal to the first linear direction, and a third sensormay sense a third position (e.g., z-position) of camera(e.g., position of lens) with respect to a third linear direction normal to the first linear direction and the second linear direction.

Camera controllermay be housed within enclosure, may be communicatively coupled to cameraand applications processor(e.g., via an Inter-Integrated Circuit (I2C) interface), and may include any system, device, or apparatus configured to control mechanical actuatorsor other components of camerato place components of camerainto a desired position. Camera controllermay also be configured to receive signals from sensorsregarding an actual position of cameraand/or regarding a status of camera. As shown in, camera controllermay include a control subsystemand current drivers.

Control subsystemmay be integral to camera controller, and may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, control subsystemmay interpret and/or execute program instructions and/or process data stored in a memory and/or other computer-readable media accessible to control subsystem. Specifically, control subsystemmay be configured to perform functionality of camera controller, including but not limited to control of mechanical actuatorsand receipt and processing of data from sensors.

Current driversmay comprise a plurality of circuits, each such circuit configured to receive one or more control signals from control subsystem(including without limitation a signal indicative of a desired target current for a mechanical actuator) and drive a current-mode signal to a respective mechanical actuatorin accordance with the one or more control signals in order to control operation of such respective mechanical actuator.

illustrates a block diagram of selected components of a control system, in accordance with embodiments of the present disclosure. As shown in, control systemmay include main controller, secondary controller, and a load. In some embodiments, control systemmay implement all or a part of camera module. For example, in such embodiments, main controllermay implement applications processor, secondary controllermay implement camera controller, and loadmay implement a mechanical actuator.

Main controllermay include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, main controllermay interpret and/or execute program instructions and/or process data stored in a memory (not explicitly shown) and/or other computer-readable media accessible to main controller.

Secondary controllermay be communicatively coupled to main controllervia a bidirectional communication channel, and may comprise any suitable system, device, or apparatus configured to drive an output current Ito loadto cause an output voltage Vacross load. As shown in, secondary controllermay include a control subsystem(which may implement control subsystem), a digital-to-analog converter (DAC)(which may implement at least a portion of current drivers), and sensor(which may implement one or more of sensors). In operation, DACmay convert a digital target current signal Ireceived from control subsysteminto an analog current signal for driving output current Ito loadto cause output voltage Vacross load. Sensorsmay sense output voltage Vand generate a measured voltage signal Vindicative of output voltage V. Further, sensorsmay sense output current Iand generate a measured current signal Iindicative of output current I.

Loadmay comprise any electrical, electromechanical, and/or electromagnetic load.

In operation, control subsystemmay, based on measured voltage signal Vand either of digital target current signal Iand or a measured current signal I, apply Ohm's law to calculate a resistance R (e.g., R=V/IOr R=V/I) associated with load(as described in greater detail below) and communicate such resistance R to main controller. However, secondary controllermay communicate such resistance R to main controllerat a time interval which is greater than a time duration of electrical transients across load. Further, the samples of output voltage Vmeasured by sensormay also be taken at a time interval that is greater than a time duration of electrical transients across load. Moreover, in some instances, measurements of output voltage Vmay be asynchronous and thus non-instantaneous with digital target current signal I. Thus, at times, the load transients, asynchronous measurements, and/or other system configurations may lead to accuracy-reducing events in the measurement of resistance, resulting in non-negligible errors in the resistance calculation computed and reported by control subsystem.

illustrates a flow chart of an example methodfor computing accurate load resistance in control system, in accordance with embodiments of the present disclosure. According to some embodiments, methodmay begin at stepA. As noted above, teachings of the present disclosure may be implemented in a variety of configurations of mobile deviceand/or control system. As such, the preferred initialization point for methodand the order of the steps comprising methodmay depend on the implementation chosen.

At stepA, control subsystemmay determine if supply voltage Vis sufficient to deliver target current Ito load. If supply voltage Vis insufficient to deliver target current Ito load, methodmay proceed to stepB. Otherwise, methodmay proceed to step.

At stepB, control subsystemmay optionally lower digital target current signal Iin order that the lowered target current signal Iis realizable with available supply voltage V. After completion of stepB, methodmay proceed to step.

At step, control subsystemmay determine if measured voltage signal Vis below a threshold voltage level. A measured voltage signal Vbelow the threshold voltage level may be too low to provide accurate resistance calculations. If measured voltage signal Vis below the threshold voltage level, methodmay proceed to step. Otherwise, methodmay proceed to step.

At step, control subsystemmay determine if measured current signal Ior digital target current signal Iis below a threshold current level. A measured current signal Ior digital target current signal Ibelow the threshold current level may be too low to provide accurate resistance calculations. If measured current signal Ior digital target current signal Iis below a threshold current level, methodmay proceed to step. Otherwise, methodmay proceed to step.

At step, control subsystemmay determine if a rate of change over time or slew rate of measured voltage signal Vis above a threshold voltage slew level. A slew rate of voltage signal Vabove the threshold voltage slew level may be too high to provide accurate resistance calculations. If the slew rate of measured voltage signal Vis above the threshold voltage slew level, methodmay proceed to step. Otherwise, methodmay proceed to step.

At step, control subsystemmay determine if a rate of change over time or slew rate of either of measured current signal Ior digital target current signal Iis above a threshold current slew level. A slew rate of measured current signal Ior digital target current signal Iabove the threshold current slew level may be too high to provide accurate resistance calculations. If the slew rate of either of measured current signal Ior digital target current signal Iis above a threshold current slew level, methodmay proceed to step. Otherwise, methodmay proceed to step.

At step, control subsystemmay determine if a rate of change over time or slew rate of a supply voltage Vthat supplies electrical energy to DACand/or other components of mobile deviceis above a threshold voltage slew level. A slew rate of supply voltage Vabove the threshold voltage slew level may be too high to provide accurate resistance calculations. If the slew rate of measured voltage signal Vis above the threshold voltage slew level, methodmay proceed to step. Otherwise, methodmay proceed to step.

At step, the magnitude of measured voltage signal V, magnitude of measured current signal Iand/or digital target current signal I, the slew rate of measured voltage signal V, the slew rate of measured current signal Iand/or digital target current signal I, the slew rate of supply voltage V, and the magnitude of supply voltage Vmay be within acceptable ranges for providing accurate resistance calculations. Accordingly, control subsystemmay calculate resistance R of loadin accordance with Ohm's law and communicate such calculated value to main controller. After completion of step, methodmay proceed again to stepA.

At step, at least one of the parameters (e.g., magnitude of measured voltage signal V, magnitude of measured current signal Iand/or digital target current signal I, the slew rate of measured voltage signal V, the slew rate of measured current signal Iand/or digital target current signal I, the slew rate of supply voltage V, and the magnitude of supply voltage V) may be within an unacceptable range for providing accurate resistance calculations. Accordingly, control subsystemmay modify information it communicates in connection with the calculation of resistance R. Such information may include status flags or may include a modification of the calculation of resistance R. Examples of such modification of the calculation of resistance R may include control subsystemreporting the previously calculated value for the calculation of resistance R to main controller, control subsystemreporting a default value (e.g., zero) for resistance R to main controller, and/or control subsystemmodifying one or more status flags reported to main controller. After completion of step, methodmay proceed again to stepA.

Althoughdiscloses a particular number of steps to be taken with respect to method, methodmay be executed with greater or fewer steps than those depicted in. In addition, althoughdiscloses a certain order of steps to be taken with respect to method, the steps comprising methodmay be completed in any suitable order.

Methodmay be implemented using a mobile device, control system, and/or any other system operable to implement method. In certain embodiments, methodmay be implemented partially or fully in software and/or firmware embodied in computer-readable media.

The conditions set forth in stepsA,,,,, andabove, that is, the magnitude of measured voltage signal Vbeing below a threshold, the magnitude of measured current signal Ior digital target current signal Ibeing below a threshold, the slew rate of measured voltage signal Vbeing above a threshold, the slew rate of measured current signal Ior digital target current signal Ibeing above a threshold, a slew rate of a supply voltage Vbeing above a threshold voltage slew level, and supply voltage Vbeing insufficient to provide digital target current signal I, may be referred to as “accuracy-reducing events.” In some embodiments, accuracy-reducing events used to determine whether to measure or suppress measurement of resistance may include only a subset of those accuracy-reducing events described above in stepsA,,,,, and. In these and other embodiments, accuracy-reducing events used to determine whether to measure or suppress measurement of resistance may include one or more of those accuracy-reducing events described above in stepsA,,,,, and, in addition to one or more accuracy-reducing events described above.

illustrates a flow chart of an example methodof calculating load resistance in the presence of asynchronous current and voltage data, in accordance with embodiments of the present disclosure. According to some embodiments, methodmay begin at step. As noted above, teachings of the present disclosure may be implemented in a variety of configurations of mobile deviceand/or control system. As such, the preferred initialization point for methodand the order of the steps comprising methodmay depend on the implementation chosen.

At step, while generating target current signal Iand measuring voltage signal Vand current signal I, control subsystemmay store sampled values of measured voltage signal Vand target current signal Iand/or measured current signal Iin individual timestamped buffers. At step, control subsystemmay time-align the samples of target current signal Iand/or measured current signal Iwith measurements of measured voltage signal Vin the buffers based on timestamps of the timestamped buffers.

At step, control subsystemmay determine if accuracy-reducing events are present based on data in the buffers. For example, control subsystemmay detect the accuracy-reducing events of stepsandof methodbased on data stored in the buffers of samples of measured voltage signal V. As another example, control subsystemmay detect the accuracy-reducing events of stepsandof methodbased on data stored in the buffers of samples of measured current signal Iand/or target current signal I. If accuracy-reducing events are absent, methodmay proceed to step. Otherwise, if accuracy-reducing events are present, methodmay proceed to step.

At step, control subsystemmay calculate load resistance from time-aligned samples using any one or more of a variety of methods known to those of skill in the art. After completion of step, methodmay proceed again to step.

At step, control subsystemmay modify information it communicates in connection to calculation of resistance R. After completion of step, methodmay proceed again to step.

Althoughdiscloses a particular number of steps to be taken with respect to method, methodmay be executed with greater or fewer steps than those depicted in. In addition, althoughdiscloses a certain order of steps to be taken with respect to method, the steps comprising methodmay be completed in any suitable order.

Methodmay be implemented using a mobile device, control system, and/or any other system operable to implement method. In certain embodiments, methodmay be implemented partially or fully in software and/or firmware embodied in computer-readable media.

As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements.

This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

Although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described above.

Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale.